<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        * {
            margin: 0;
            padding: 0;
        }

        body {
            background-color: #333;
        }

        .bg {
            position: fixed;
            width: 100%;
            height: 100vh;
            background: url(https://p5.itc.cn/images01/20220512/dbd5c7e58b494784989d777b11cf50cc.jpeg);
            background-size: 100%;
            background-repeat: no-repeat;
            cursor: pointer;
            box-sizing: border-box;
            clip-path: circle(80px at var(--x) var(--y));
        }

        .bg:active {
            transform: scale(1.2);
            transition: all 0.12s;
            clip-path: circle(240px at var(--x) var(--y));
        }
    </style>
</head>

<body>
    <div class="bg"></div>
    <script>
        let bg = document.documentElement
        bg.addEventListener('mousemove', (e) => {
            bg.style.setProperty('--x', e.clientX + 'px')
            bg.style.setProperty('--y', e.clientY + 'px')
        })
    </script>
</body>

</html>